Which longitude is designated as the International Date

Solution

The International Date Line (IDL) is located at approximately 180° longitude, opposite the Prime Meridian (0° longitude). It is not a perfectly straight line but zigzags to avoid dividing land areas and island groups. When crossing the IDL from east to west, a day is added to the calendar; when crossing from west to east, a day is subtracted. This imaginary line serves as the point where the date changes by one day when crossed.